networking: make skb_push & __skb_push return void pointers

It seems like a historic accident that these return unsigned char *,
and in many places that means casts are required, more often than not.

Make these functions return void * and remove all the casts across
the tree, adding a (u8 *) cast only where the unsigned char pointer
was used directly, all done with the following spatch:

    @@
    expression SKB, LEN;
    typedef u8;
    identifier fn = { skb_push, __skb_push, skb_push_rcsum };
    @@
    - *(fn(SKB, LEN))
    + *(u8 *)fn(SKB, LEN)

    @@
    expression E, SKB, LEN;
    identifier fn = { skb_push, __skb_push, skb_push_rcsum };
    type T;
    @@
    - E = ((T *)(fn(SKB, LEN)))
    + E = fn(SKB, LEN)

    @@
    expression SKB, LEN;
    identifier fn = { skb_push, __skb_push, skb_push_rcsum };
    @@
    - fn(SKB, LEN)[0]
    + *(u8 *)fn(SKB, LEN)

Note that the last part there converts from push(...)[0] to the
more idiomatic *(u8 *)push(...).

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 3 insertions, 5 deletions

diff --git a/drivers/firewire/net.c b/drivers/firewire/net.c
index d5040bbd34e8..242359c2d1f1 100644
--- a/drivers/firewire/net.c
+++ b/drivers/firewire/net.c
@@ -219,7 +219,7 @@ static int fwnet_header_create(struct sk_buff *skb, struct net_device *net,
 {
         struct fwnet_header *h;
 
-        h = (struct fwnet_header *)skb_push(skb, sizeof(*h));
+        h = skb_push(skb, sizeof(*h));
         put_unaligned_be16(type, &h->h_proto);
 
         if (net->flags & (IFF_LOOPBACK | IFF_NOARP)) {
@@ -961,16 +961,14 @@ static int fwnet_send_packet(struct fwnet_packet_task *ptask)
         tx_len = ptask->max_payload;
         switch (fwnet_get_hdr_lf(&ptask->hdr)) {
         case RFC2374_HDR_UNFRAG:
-                bufhdr = (struct rfc2734_header *)
-                                skb_push(ptask->skb, RFC2374_UNFRAG_HDR_SIZE);
+                bufhdr = skb_push(ptask->skb, RFC2374_UNFRAG_HDR_SIZE);
                 put_unaligned_be32(ptask->hdr.w0, &bufhdr->w0);
                 break;
 
         case RFC2374_HDR_FIRSTFRAG:
         case RFC2374_HDR_INTFRAG:
         case RFC2374_HDR_LASTFRAG:
-                bufhdr = (struct rfc2734_header *)
-                                skb_push(ptask->skb, RFC2374_FRAG_HDR_SIZE);
+                bufhdr = skb_push(ptask->skb, RFC2374_FRAG_HDR_SIZE);
                 put_unaligned_be32(ptask->hdr.w0, &bufhdr->w0);
                 put_unaligned_be32(ptask->hdr.w1, &bufhdr->w1);
                 break;